>>> "Kevin Grittner" <Kevin.Grittner@xxxxxxxxxxxx> wrote: > I'm going to get the latest snapshot to see if the issue has changed > for 8.4devel In testing under today's snapshot, it seemed to take 150,000 writes to create and drop 1,000 temporary tables within a database transaction. The numbers for the various versions might be within the sampling noise, since the testing involved manual steps and required saturating the queues in PostgreSQL, the OS, and the RAID controller to get meaningful numbers. It seems like the complaints of slowness result primarily from these writes saturating the bandwidth when a query generates a temporary table in a loop, with the increased impact in later releases resulting from it getting through the loop faster. I've started a thread on the hackers' list to discuss a possible PostgreSQL enhancement to help such workloads. In the meantime, I think I know which knobs to try turning to mitigate the issue, and I'll suggest rewrites to some of these queries, to avoid the temporary tables. If I find a particular tweak to the background writer or some such is particularly beneficial, I'll post again. -Kevin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
